A Chinese female Morvan patient with LGI1 and CASPR2 antibodies: a case report

Clinicopathological Features in Morvan's Syndrome: An Autopsy Case Study

Morvan's syndrome is a rare, complex autoimmune syndrome comprising peripheral nerve hyperexcitability, dysautonomia, insomnia, and encephalopathy. In this case report, we highlight the clinical and pathological findings of an elderly gentleman who presented to us with clinical features of Morvan's syndrome associated with anti-contactin-associated protein 2 (CASPR-2) antibodies. Histopathology [Figure 3] revealed cortical atrophy with gliosis and mild microglial proliferation. Microglial activation and gliosis were observed in the hippocampus, hypothalamus, and thalamus. Brainstem showed multifocal inflammation. Mild inflammation was observed in the leptomeninges. Morvan's syndrome is an autoimmune disease with antibodies targeted against CASPR within the voltage-gated potassium channel (VGKC) complex. Early diagnosis and treatment play a key role in the management of patients. Most patients show a good response when treated with plasmapheresis and steroids. This patient presented to us late into the illness and succumbed.

Stimulus-Induced Motor Afterdischarges in CASPR2 (Contactin-Associated Protein-Like 2)-Positive Peripheral Nerve Hyperexcitability Syndrome

Peripheral nerve hyperexcitability is an uncommon but treatable condition in neurology. Voltage-gated potassium channelopathies, especially contactin-associated protein-like 2 (CASPR2) antibody, are commonly implicated. We present the case of a 16-year-old boy with tremulousness of both feet and twitching of muscles all over the body for three months. Examination revealed irregular, arrhythmic, small-amplitude twitching movements of the toes along with fasciculations in both thighs. Nerve conduction studies were within normal limits. F-wave studies showed a prolonged polyphasic large-amplitude discharge following the compound muscle action potential and obscuring the F waves. Electromyography showed extensive myokymic discharges. The serum autoimmune antibody profile showed strong positivity for CASPR2. He started lacosamide as a symptomatic treatment. In view of the good symptomatic response, further immunomodulation was deferred and he remains on follow-up. We present this case to highlight the role of motor afterdischarges as a diagnostic clue to peripheral nerve hyperexcitability and to review the literature on this interesting finding.

Case report: Anti-IgLON5 disease and anti-LGI1 encephalitis following COVID-19

Anti-IgLON family member 5 (IgLON5) disease is a rare autoimmune encephalitis, characterized by sleep problems, cognitive decline, gait abnormalities, and bulbar dysfunction. Anti-leucine-rich glioma-inactivated 1 (LGI1) autoimmune encephalitis is characterized by cognitive dysfunction, mental disorders, faciobrachial dystonic seizures (FBDS), and hyponatremia. Various studies report that coronavirus disease 2019 (COVID-19) have an effect on the nervous system and induce a wide range of neurological symptoms. Autoimmune encephalitis is one of the neurological complications in severe acute respiratory syndrome coronavirus 2 infection. Until now, autoimmune encephalitis with both anti-IgLON5 and anti-LGI1 receptor antibodies following COVID-19 is rarely reported. The case report described a 40-year-old man who presented with sleep behavior disorder, daytime sleepiness, paramnesia, cognitive decline, FBDS, and anxiety following COVID-19. Anti-IgLON5 and anti-LGI1 receptor antibodies were positive in serum, and anti-LGI1 receptor antibodies were positive in cerebrospinal fluid. The patient presented with typical symptoms of anti-IgLON5 disease such as sleep behavior disorder, obstructive sleep apnea, and daytime sleepiness. Moreover, he presented with FBDS, which is common in anti-LGI1 encephalitis. Therefore, the patient was diagnosed with anti-IgLON5 disease and anti-LGI1 autoimmune encephalitis. The patient turned better after high-dose steroid and mycophenolate mofetil therapy. The case serves to increase the awareness of rare autoimmune encephalitis after COVID-19.

Peripheral nerve hyperexcitability syndrome: A clinical, electrophysiological, and immunological study

INTRODUCTION

Peripheral nerve hyperexcitability syndrome (PNHS) is characterized by muscle fasciculations and spasms. Nerve hyperexcitability and after-discharges can be observed in electrophysiological studies. Autoimmune mechanisms play a major role in the pathophysiology of primary PNHS.

METHODS

We retrospectively conducted a case-control study recruiting patients with clinical and electrophysiological features of PNHS. Control patients were diagnosed with other neuronal or muscular diseases. Contactin-associated protein2 (CASPR2) and leucine-rich glioma-inactivated1 (LGI1) antibodies were examined.

RESULTS

A total of 19 primary PNHS patients and 39 control patients were analyzed. The most common symptoms for the case group were fasciculations (11/19) and muscle spasms (13/19). Case group patients were likely to demonstrate electrodiagnostic findings of nerve hyperexcitability (17/19) and after-discharges in the tibial nerve (19/19). We found high prevalence of CASPR2 (9/19) and LGI1 (6/19) antibodies in the case group.

DISCUSSION

Primary PNHS patients were likely to show after-discharges in the tibial nerve. The pathogenesis of PNHS is autoimmune CASPR2 and LGI1 antibodies are possible pathogenic antibodies for primary PNHS.

Clinical characteristics of patients double positive for CASPR2 and LGI1-antibodies

OBJECTIVES

This study described the clinical characteristics of autoimmune neurological diseases with dual seropositive antibodies of CASPR2 and LGI1.

PATIENTS AND METHODS

Three patients, with antibodies targeting both CASPR2 and LGI1 (EUROIMMUN, FA 112d-1, Germany), hospitalized in Department of Neurology, Xuanwu Hospital, Capital Medical University from June 2016 to June 2019 were collected in this study. We summarized the clinical characteristics of patients with CASPR2 and LGI1 antibodies from a targeted literature review.

RESULTS

Three patients reported were all middle-aged and elderly male with diverse neurological symptoms, including seizures, psychological abnormalities, limb weakness and hyperhidrosis. Interestingly, three patients displayed three different clinical syndromes (isolated epilepsy, Morvan syndrome and limbic encephalitis, respectively). White blood cell and glucose in Cerebrospinal fluid (CSF) were normal and CSF for protein was slightly elevated. Electromyography (EMG) showed abnormal spontaneous firing in case 2. Brain magnetic resonance imaging (MRI) revealed bilateral hyper-intensity of the temporal lobe on T2 and FLAIR sequence in case 3. Cancer screening program of patient 2 showed thymoma. Cell based assay was positive in serum for both LGI1 and CASPR2 antibodies, while these antibodies were negative in CSF. They were treated with glucocorticoid or intravenous immunoglobulin (IVIG). Followed up for 6 months to 1 year, all patients got remission to different extent.

CONCLUSION

Through the detailed analysis of three patients, the combination of both antibodies contributes to a broad spectrum of neurological symptoms in the central, peripheral, and autonomic nervous systems. The patients with same antibodies can have different clinical syndromes. Early tumor screening and immunotherapy will improve the prognosis of the disease.

Morvan Syndrome and Diffuse Large B-Cell Lymphoma in the Central Nervous System

INTRODUCTION

The origin of contactin-associated protein-like 2 (Caspr2) antibodies in patients with Morvan syndrome is currently unknown. This case report investigated a possible association between the production of Caspr2 antibodies and aberrant proliferation of B lymphocytes.

CASE REPORT

We admitted a critically ill 65-year-old female patient with a suspected infection of the central nervous system (CNS). In addition to acquired neuromyotonia and CNS involvement, Caspr2 antibodies detected in her serum led to the presumptive diagnosis of Morvan syndrome. However, steroid and immunoglobulin treatment did not result in a satisfactory therapeutic outcome. On the basis of findings from immunohistochemistry, flow cytometric analysis, and immunoglobulin/T-cell receptor gene rearrangement detection of cerebrospinal fluid cells, we also made a concurrent diagnosis of diffuse large B-cell lymphoma in the CNS of this patient. The patient then received 4 cycles of rituximab and methylprednisolone therapy with an interval of 2 weeks, which temporarily led to a near-complete remission of her symptoms. Upon follow-up, her symptoms relapsed at 3 months after the last treatment with rituximab and methylprednisolone.

CONCLUSIONS

This is a first reported case of a patient who was concurrently diagnosed with Morvan syndrome and diffuse large B-cell lymphoma in the CNS. Additional studies are needed to determine whether aberrantly proliferating B lymphocytes are responsible for the production of Caspr2 antibodies.

Insomnia and Dysautonomia with Contactin-Associated Protein 2 and Leucine-Rich Glioma Inactivated Protein 1 Antibodies: A "Forme Fruste" of Morvan Syndrome?

Morvan syndrome (MoS) is typically characterized by neuromyotonia, sleep dysfunction, dysautonomia, and cognitive dysfunction. However, MoS patients with mild peripheral nerve hyperexcitability (PNH) or encephalopathy features have been described. A 46-year-old woman presented with a 2-month history of constipation, hyperhidrosis, and insomnia. Neurologic examination revealed muscle twitching and needle electromyography showed myokymic discharges in all limbs. No clinical or electrophysiological features of neuromyotonia were present. Although the patient denied any cognitive symptoms, neuropsychological assessment revealed executive dysfunction, while other cognitive domains were preserved. Cranial and spinal MRIs were unrevealing and tumor investigation proved negative. Polysomnography examination revealed total insomnia, which was partially reversed upon immune-modulatory therapy. Investigation of a broad panel of antibodies revealed serum leucine-rich glioma inactivated protein 1 and contactin-associated protein 2 antibodies. The features of this case indicate that the presentation of PNH syndromes may show significant variability and that MoS patients may not necessarily exhibit full-scale PNH and encephalopathy symptoms.

Mapping autoantigen epitopes: molecular insights into autoantibody-associated disorders of the nervous system

BACKGROUND

Our knowledge of autoantibody-associated diseases of the central (CNS) and peripheral (PNS) nervous systems has expanded greatly over the recent years. A number of extracellular and intracellular autoantigens have been identified, and there is no doubt that this field will continue to expand as more autoantigens are discovered as a result of improved clinical awareness and methodological practice. In recent years, interest has shifted to uncover the target epitopes of these autoantibodies.

MAIN BODY

The purpose of this review is to discuss the mapping of the epitope targets of autoantibodies in CNS and PNS antibody-mediated disorders, such as N-methyl-D-aspartate receptor (NMDAR), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), leucine-rich glioma-inactivated protein 1 (Lgi1), contactin-associated protein-like 2 (Caspr2), myelin oligodendrocyte glycoprotein (MOG), aquaporin-4 (AQP4), 65 kDa glutamic acid decarboxylase (GAD65), acetylcholine receptor (AChR), muscle-specific kinase (MuSK), voltage-gated calcium channel (VGCC), neurofascin (NF), and contactin. We also address the methods used to analyze these epitopes, the relevance of their determination, and how this knowledge can inform studies on autoantibody pathogenicity. Furthermore, we discuss triggers of autoimmunity, such as molecular mimicry, ectopic antigen expression, epitope spreading, and potential mechanisms for the rising number of double autoantibody-positive patients.

CONCLUSIONS

Molecular insights into specificity and role of autoantibodies will likely improve diagnosis and treatment of CNS and PNS neuroimmune diseases.

Paraneoplastic Morvan's syndrome following surgical treatment of recurrent thymoma: A case report

Morvan's syndrome (MoS) is a rare, complex neurological disorder characterized by neuromyotonia, neuropsychiatric features, dysautonomia and neuropathic pain. The majority of MoS cases have a paraneoplastic aetiology, usually occurring prior to the diagnosis of the underlying tumour and showing improvement following its treatment. The present study reports the case of a 35-year-old Caucasian male patient who was diagnosed with stage IVA thymoma. Thymectomy, lung resection, diaphragmatic pleurectomy and pericardio-phrenectomy were performed 6 months after neoadjuvant chemotherapy. The pathological evaluation revealed a type B2-B3 thymoma with focal squamous differentiation. Two years later, the patient underwent new surgical treatment for a local recurrence of the same histological type, and 4 weeks later, the patient presented with complex neurological symptoms compatible with MoS, including neuromyotonia, neuropsychiatric features, dysautonomia and neuropathic pain. Electromyography was compatible with a diagnosis of neuromyotonia. Brain magnetic resonance imaging scan and tests for serum anti-acetylcholine receptor, anti-striated muscle antibodies and anti-30-kDa titin fragment antibodies were all negative, whereas tests for anti-voltage-gated potassium channel (VGKC)-complex antibodies (333.3 pmol/l), anti-leucine-rich glioma inactivated protein 1 and anti-contactin-associated protein-like 2 antibodies were positive. The patient underwent 3 cycles of intravenous administration of immunoglobulins (0.4 g/kg/day for 5 days every 4 weeks) with little clinical and electrophysiological improvement. We speculated that the late onset of the symptoms in the present patient may have been triggered by an increase in the serum level of anti-VGKC antibody, which was caused by the surgery performed for the treatment of recurrent thymoma. To the best of our knowledge, the present report is the first case of MoS associated with this histological type of thymoma uncommonly occurring upon surgical treatment of recurrent thymoma.